Known window units, such as a skylight window, utilize a power unit which can cause extension and retraction of a chain connected to a movable sash of the window for causing opening and closing movement of the window sash. Window operators for skylight windows are known in the art. An example of such a window operator is shown in Tacheny et al. U.S. Pat. No. 4,521,993, owned by the assignee of this application, and the disclosure of which is hereby incorporated by reference herein. This window operator has a chain storable within a housing with the chain being extended from and retracted into the housing by means of a rotatable drive sprocket having a toothed relation with the chain.
The Tacheny et al. patent discloses a two-part housing with a housing base providing for chain storage, chain guiding, and rotatable mounting of the drive sprocket. An upper part of the housing mounts means for driving the rotatable drive sprocket which can either be a manually operable means or a motor drive, as shown in FIG. 5 of the patent.
Prior motorized window operators have used cams to actuate switches which provide direct deenergization of power to the motor at the end of the stroke. However, such operators have proven difficult to adjust.
In certain applications, such as with a larger and heavier window, multiple window operators are required to effectively and safely open and close the window. However, uneven movement of the respective actuators can cause damage to the window. This damage may be in the form of a warped window frame, broken hinges, broken drive chains or a broken window pane.
The present invention is intended to overcome one or more of the problems as set forth above.